JPH0922669A - Image display device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device to be applied to a picture tube or the like, which is provided with a reflection lowering function and a charge preventing function without hindering the characteristic of image at a high resolution and at a high contrast and which can prevent the finger print and the adhesion of spotting, by forming a conductive high refraction index thin film in the glass side and forming a water repellent low refractive index thin film outside of the conductive high refractive index thin film. SOLUTION: As an inner layer 2, a transparent and conductive high refractive index thin film at 1.65 of refractive index is evenly formed at 85nm of film thickness (t1 ) on the outer surface of a face panel glass 1 at 1.54 of refractive index, and as an outer layer 3, a low refractive index thin film at 1.42 of refractive index, which has methyl group, is evenly formed at 99nm of film thickness (t1 ) on the surface of the inner layer 2. Optical film thickness of the high refractive index thin film as the inner layer 2 and the low refractive index thin film as the outer layer 3 are set at 140nm at 1/4 of the wavelength at 560nm at a high luminosity among the outside light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device such as a picture tube or a plasma display panel having a function of reducing reflection of external light, and a manufacturing method thereof.

[0002]

2. Description of the Related Art When external light from an indoor illumination lamp or the like is reflected on the outer surface of a glass face panel of an image display device such as a picture tube, a reproduced image becomes very difficult to see. Further, when static electricity is accumulated on the outer surface of the face panel, not only dust may easily adhere to the face panel, but also a risk of electric shock may occur. As means for solving this, for example, in Japanese Patent Laid-Open No. 5-67432, a volatile solution containing tin oxide and silicon oxide is spin-coated on the outer surface of a face panel and dried to obtain a first layer, A volatile solution containing silicon oxide is spin-coated and dried to obtain a second layer which is a surface layer, and the composite film obtained by baking is subjected to an interference action so that the light reflectance on the outer surface of the face panel is about 1%. A method is disclosed in which the antistatic effect can be obtained at the same time as 0.5% or less.

[0003]

However, in the above-mentioned conventional structure, since it is a smooth film, there is no problem that the resolution and contrast of the displayed image are deteriorated, but on the other hand, fingerprint marks called fingerprints are visible. Easy to remove and difficult to remove. Further, if water drops are left for a long time when wiping with water, there is a problem that a stain mark that shines blue remains.

There is also a method for preventing the fingerprint from adhering by providing irregularities on the outermost surface, but the irregularities cause the light emitted from the phosphor screen to be scattered and reduce the resolution, and the contrast due to scattered reflection of external light. There is a problem such as lowering.

In order to solve the above-mentioned conventional problems, the present invention has a reflection reduction function and an antistatic function without impairing the characteristics of a high-resolution, high-contrast image, and prevents the adhesion of fingerprints and stain marks. It is an object of the present invention to provide an image display device excellent in a picture tube and the like and a manufacturing method thereof.

[0006]

In order to achieve the above object, the image display device of the present invention is an image display device having an antireflection film on the surface of a glass face panel, which has a conductive high refractive index on the glass side. A thin film is formed, and an antireflection film in which a water-repellent low refractive index thin film is laminated is formed on the outer layer thereof. In the above description, the term "conductive" refers to an electric resistance in the range of 10 < ² > to 10 < ¹¹ > [Omega] /-(by defining sheet resistance or other indications, the conductive range in the present invention). The water repellency referred to in the present invention means that the contact angle with water is 40 ° or more.

In the above, it is preferable that the water-repellent low refractive index thin film is made of methyl group-containing silicon oxide. In the above, the water-repellent low refractive index thin film has a refractive index of 1.4 to 1.
5 and a film thickness of 70 to 150 nm are preferable.

In the above, the conductive high refractive index thin film contains at least one oxide selected from silicon oxide, titanium oxide, tin oxide and antimony oxide, and has a refractive index in the range of 1.6 to 2.0. The film thickness is preferably in the range of 7 to 130 nm.

Next, the manufacturing method of the image display device of the present invention is as follows.
In a method for manufacturing an image display device having an antireflection film on the surface of a glass face panel, a conductive high refractive index thin film is formed on the glass face panel, and then an alkyl silicate polymer is dissolved in an alcohol-based solution. It is characterized in that a water-repellent low-refractive-index thin film is formed by applying a mixed solution containing methyltrimethoxysilane to the solution and then heating it.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the configuration of the present invention described above,
In an image display device having an antireflection film on the surface of a glass face panel, a conductive high refractive index thin film is formed on the glass side, and an antireflection film in which a water-repellent low refractive index thin film is laminated is formed on the outer layer thereof. Therefore, an image display device that has a reflection reduction function and an antistatic function without impairing the characteristics of a high-resolution, high-contrast image, and that is excellent for a picture tube that prevents the attachment of fingerprints and spots is provided. Can be provided. That is, since the surface is water-repellent, the fingerprints can be easily wiped off, and even when wiping with water, water droplets are less likely to remain, and silanol groups (-SiOH) that easily react with impurities such as calcium are used instead. since that is the reaction hardly methylsilyl group (-SiCH _3), though the hard remaining stains traces due to the adhesion of impurities such as calcium also remains water droplets.

Further, by modifying the silicon oxide with a methyl group, the refractive index of the low refractive index layer can be lowered as compared with the case where only silicon oxide is used. By the way, the minimum value R of the reflectance with respect to the external light incident on the surface is such that the optical film thickness of each of the high refractive index thin film and the low refractive index thin film (the value obtained by multiplying the actual film thickness by the refractive index) is a predetermined value. In the case of 1/4 of the wavelength λ, it is represented by the following formula (Formula 1). As is clear from this formula (Formula 1), the reflection reduction effect can be improved by lowering the refractive index of the low refractive index layer. .

[0012]

[Equation 1]

Here, n _s is the refractive index of the face panel, n _l is the refractive index of the low refractive index layer, n _h is the refractive index of the high refractive index layer, and n ₀ is the refractive index of air. Next, according to the method of the present invention, an image display device can be provided efficiently and rationally.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an overall view of a picture tube using the present invention as an embodiment of the present invention. The picture tube 21 comprises a face panel 1 having a fluorescent screen (not shown) and a funnel 22 therein. An anode button 23 for supplying an anode voltage from a high voltage power source is embedded in the funnel 22. At the rear end of the funnel 22, a neck portion 24 having an electron gun (not shown) inside is formed.
Is provided. A predetermined drive voltage is applied to each electrode of the electron gun from the last end of the neck portion via a stem pin (not shown). A deflection yoke 26 for scanning an electron beam emitted from an electron gun on the fluorescent screen is provided outside the boundary between the funnel portion 22 and the neck portion 24. Further, 25 is a socket and 27 is a reinforcing band.

Next, FIG. 1 is an enlarged cross-sectional view of a main part of a picture tube which is an embodiment of the present invention. A conductive high refractive index thin film 2 and a water repellent low refractive index thin film 3 are laminated on the surface of a glass substrate 1, and a methyl group 4 is present in the water repellent low refractive index thin film 3. The manufacturing process will be described below. (1) High Refractive Index Thin Film Forming Step On the outer surface of the face panel glass 1 having a refractive index of 1.54, a transparent conductive refractive index made of tin oxide doped with silicon oxide, titanium oxide and antimony as the inner layer 2 is formed. A high refractive index thin film of 1.65 (thickness t ₂ is 85 nm) is formed. To obtain a uniform thin film of this high refractive index thin film,
A solution prepared by hydrolyzing and copolymerizing tetraethyl silicate and tetrabutyl titanate in an ethanol solvent in the presence of hydrochloric acid and uniformly dispersing fine particles of tin oxide doped with antimony having an average diameter of about 10 nm is applied by spin coating. Then, it is heated to about 60 ° C. to form the inner layer 2. (2) Low Refractive Index Thin Film Forming Step Next, on the surface of the high refractive index thin film, a transparent low refractive index thin film having a refractive index of 1.42 made of silicon oxide containing a methyl group as the outer layer 3 has a thickness t _1. A uniform thin film of 99 nm is formed. In order to obtain this film, tetraethyl silicate is hydrolyzed in an ethanol solvent in the presence of hydrochloric acid, and a solution obtained by polymerizing is added as methyltrimethoxysilane, for example, S manufactured by Toray Dow Corning Silicone Co., Ltd.
A solution in which Z6070 (product name) was added at a weight ratio of tetraethyl silicate of methyltrimethoxysilane: tetraethylsilicate = 1: 1 was applied by spin coating, dried by heating to 60 ° C., and then heated to 400 ° C. And bake.

As described above, a two-layer antireflection film composed of the inner layer 2 and the outer layer 3 is formed. The high-refractive-index thin film of the inner layer 2 and the low-refractive-index thin film of the outer layer 3 have an optical film thickness of (1/4) λ of the wavelength of λ = 560 nm, which is a wavelength having high visibility in external light. It is 140 nm.

The outer layer 3 of the antireflection film has a chemical structure as shown in FIG. 3, and the methyl groups 4 appearing on the surface make the contact angle of water 80 ° to be water-repellent to prevent the attachment of dirt. You can

As a result of a water stain adhesion test in which tap water was dropped and allowed to stand for 24 hours, when the conventional outer layer was formed only of silicon oxide, strongly adhered water stain was generated and the exposed cloth ( Although it was not possible to remove water stains by wiping with a cotton cloth) with a blank cloth or water, in the picture tube of the embodiment of the present invention, water droplets do not remain due to the water repellency of the surface, and water stains do not occur. It was Also, when water drops are forced to remain, water stains adhere, but they could be removed by lightly exposing and wiping with a cloth.

Further, in the conventional antireflection film, a stain mark that shines blue remained when wiped with water, but such a stain mark did not occur in the embodiment of the present invention. this is,
In the conventional antireflection film, impurities such as calcium in water are silicon oxide (Si) which is a low refractive index thin film of the antireflection film.
O ₂ ), which is chemically bonded to the hydroxyl group (-SiOH) remaining in the film and strongly adheres to the surface, and the relationship of the film thickness for reduction of reflection due to the interference action is broken, resulting in a blue glowing stain mark. In contrast to this, it is considered that the balance of the film thickness is not lost in the present invention.

As a reference, FIG. 4 shows the chemical structure in the case where the outer layer 3 is formed of only silicon oxide. Hydroxyl groups 5 appear on the surface, and therefore the surface is hydrophilic with a contact angle of water of 5 °. In addition, impurities such as calcium contained in water bond with the hydroxyl groups and firmly adhere to them. Originally, the optical film thicknesses of the high-refractive-index thin film of the inner layer 2 and the low-refractive-index thin film of the outer layer 3 are ¼ of the predetermined wavelength λ of the external light, as shown in the schematic diagram of reflection reduction shown in FIG. In addition, the phases of the reflected light 7 at the interface between the face panel and the inner layer 2, the reflected light 8 at the interface between the inner layer 2 and the outer layer 3, and the reflected light 9 at the surface of the outer layer 3 are exactly the same with respect to the external light 6 having a predetermined wavelength. While the reflected light of the combined light 10 of the respective reflected lights is reduced by the interference effect due to the overlapping so as to cancel each other, the thin film made of impurities such as calcium is formed on the surface of the outer layer 3 and the relation of the film thickness is formed. As shown in the schematic view of the reflected light at the water stain portion in FIG. 6, the reflected light at the interface between the face panel and the inner layer 2 with respect to the external light 6 having a predetermined wavelength depending on the film thickness of the thin film 11 due to impurities. 7 ', reflected light 8'at the interface between the inner layer 2 and the outer layer 3 and Overlap as each phase of the reflected light of the reflected light 9 'on the object surface is constructive, the combined light 10
’Intensifies and water spots shine.

Further, by modifying the surface of the outer layer again with a methyl group, the refractive index of the outer layer 3 which is a low refractive index layer can be lowered from 1.47 to 1.42, which is the minimum value of the above-mentioned reflectance. As can be seen from the equation (1), the minimum value of the reflectance is 1.00% from the conventional value of 1.00% as an antireflection effect.
It can be improved to 43%. Magnesium fluoride (MgF ₂ ) is known as a material capable of obtaining a thin film having such a low refractive index, but when a thin film is formed of silicon oxide containing magnesium fluoride, the strength of the thin film is There is a problem that it becomes whitish due to its weakness and diffuse reflection of fine particles of magnesium fluoride, resulting in a decrease in transparency. On the other hand, the thin film of silicon oxide containing a methyl group of the present invention has a film strength increased rather than a thin film of only silicon oxide, and a very transparent thin film can be obtained.

In order to obtain a silicon oxide thin film modified with a methyl group, it is conceivable to add trimethylmethoxysilane or dimethyldimethoxysilane instead of adding methyltrimethoxysilane in the above-mentioned embodiment. When the reaction with tetraethyl silicate is insufficient, trimethylmethoxysilane volatilizes in the process of forming the thin film and variations in the film thickness easily occur, and dimethyldimethoxysilane itself undergoes self-polycondensation to form silicon oil, There is a problem that the coating liquid repels and a thin film cannot be formed.

In the above example, methyltrimethoxysilane was added in a weight ratio of tetraethylsilicate to methyltrimethoxysilane: tetraethylsilicate = 1: 1, but the weight ratio of methyltrimethoxysilane to tetraethylsilicate in Table 1 was added. As shown in the relationship between the contact angle of water with water, the refractive index of the upper layer, the degree of water stain, and the effect of reducing reflection, the amount of methyltrimethoxysilane added was 2: 5 by weight ratio of methyltrimethoxysilane: tetraethylsilicate.
When the amount is larger than that, improvement in water repellency and refractive index is observed. However, when the input amount of methyltrimethoxysilane is more than 2: 1 by weight ratio of methyltrimethoxysilane: tetraethylsilicate, methyltrimethoxysilane does not sufficiently react with tetraethylsilicate and methyltrimethoxysilane does not react during heating or firing. Is volatilized and the film thickness is not constant, making it difficult to control the film thickness. For this reason, it is appropriate that the amount of methyltrimethoxysilane added be 2: 5 to 2: 1 in terms of the weight ratio of methyltrimethoxysilane: tetraethylsilicate.

[0024]

[Table 1]

In the above embodiment, spin coating was used as the coating method, but general uniform film forming methods such as dip coating and spray coating may be used. The firing temperature may be in the range of 150 ° C. at which practical film strength is obtained to 500 ° C. at which methyl groups are not decomposed.

Although a transparent conductive film made of tin oxide doped with silicon oxide, titanium oxide and antimony was used as the inner layer 2, indium tin oxide may be used instead of tin oxide doped with antimony, and CVD A tin oxide film formed by the method can also be used.

Further, although the case where the predetermined wavelength of the external light is 560 nm, which has high visibility, has been described, the present invention is not limited to this. In the above embodiment, the picture tube is explained, but PD
The same effect can be obtained when used in other image display devices such as P and LCD. In this case, when the refractive index differs from that of the above embodiment due to the difference in the material of the face glass panel, the same effect can be obtained by appropriately adjusting the film thickness of each layer constituting the antireflection film.

[0028]

According to the image display device of the present invention, even if the fingerprint is attached, the fingerprint can be removed by lightly wiping with water. In addition, water stains do not easily adhere to water stains, and even if they adhere, they can be removed by lightly wiping with water, and they will not adhere strongly, and a stable antireflection effect can be realized.

Further, in the image display device of the present invention, the minimum value of the surface reflectance by external light is 0.65 to 0.43%, and an excellent antireflection effect can be obtained, and the surface reflectance by the external light such as indoor lighting can be obtained. It is possible to prevent the reproduced image from being difficult to see and improve the contrast of the image.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part of an image display device according to an embodiment of the present invention.

FIG. 2 is a schematic side view showing the overall configuration of a picture tube which is an embodiment of the present invention.

FIG. 3 is a chemical structure diagram of an outer layer in the antireflection film of the image display device according to the embodiment of the present invention.

FIG. 4 is a chemical structure diagram of an outer layer in an antireflection film of a conventional image display device.

FIG. 5 is a schematic diagram of reflection reduction.

FIG. 6 is a schematic diagram of reflected light from a water stain part.

[Explanation of symbols]

 1 Face Panel Glass 2 Inner Layer 3 Outer Layer 4 Methyl Group 5 Hydroxyl Group 6 Incident Light 7, 7 ', 8, 8', 9, 9'Reflected Light 10 Synthetic Light 11 Thin Film Due to Impurities 21 Funnel 23 Funnel 23 Anode Button 24 Neck Part 25 socket 26 deflection yoke 27 reinforcement band

Claims (5)

[Claims] 1. An image display device having an antireflection film on the surface of a glass face panel, wherein a conductive high refractive index thin film is formed on the glass side, and a water-repellent low refractive index thin film is laminated on the outer surface thereof. An image display device having a protective film formed thereon. 2. The image display device according to claim 1, wherein the water-repellent low refractive index thin film is made of methyl group-containing silicon oxide. 3. The water-repellent low refractive index thin film has a refractive index of 1.4 to
The image display device according to claim 1, wherein the image display device has a range of 1.5 and a film thickness of 70 to 150 nm. 4. The conductive high refractive index thin film is silicon oxide,
It contains at least one oxide selected from titanium oxide, tin oxide, and antimony oxide, and has a refractive index of 1.6 to
The image display device according to claim 1, wherein the image display device has a thickness of 2.0 and a thickness of 7 to 130 nm. 5. A method of manufacturing an image display device having an antireflection film on the surface of a glass face panel, wherein a conductive high refractive index thin film is formed on the glass face panel, and then an alkyl silicate polymer is added to alcohol. A method for producing an image display device, comprising forming a water-repellent low refractive index thin film by applying a mixed solution prepared by adding methyltrimethoxysilane to a solution dissolved in a system solution and then heating.